Substrate liquid processing apparatus, substrate liquid processing method and storage medium

ABSTRACT

A substrate liquid processing apparatus includes a liquid processing unit configured to store a processing liquid and a substrate and process the substrate using the processing liquid, the processing liquid including a phosphoric acid aqueous solution; a phosphoric acid aqueous solution supply unit configured to supply the phosphoric acid aqueous solution to the liquid processing unit; a discharge line connected to the liquid processing unit, and configured to discharge the processing liquid; a return line switchably connected to the discharge line, and configured to return the processing liquid to the liquid processing unit; a recycling line switchably connected to the discharge line, and including a recycling unit configured to recycle the processing liquid; and a waste line switchably connected to the discharge line, and configured to discard the processing liquid to the outside.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/636,069, filed on Jun. 28, 2017, which claims priority from JapanesePatent Application No. 2016-133560, filed on Jul. 5, 2016 with the JapanPatent Office, all of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a substrate liquid processingapparatus that performs a liquid processing on a substrate using aprocessing liquid, a substrate liquid processing method and a storagemedium.

BACKGROUND

When, for example, a semiconductor component or a flat panel display ismanufactured, a substrate liquid processing apparatus is used to performa liquid processing on a substrate such as a semiconductor wafer or aliquid crystal substrate using a processing liquid such as an etchingliquid.

For example, a substrate liquid processing apparatus disclosed inJapanese Patent Laid-Open Publication No. 2013-093478 performs a processof immersing a substrate in a processing liquid (an etching liquid: aphosphoric acid aqueous solution) stored in a processing bath, andetching a silicon nitride film formed on the surface of the substrate.

Meanwhile, in the conventional art, the phosphoric acid aqueous solutionused as a processing liquid contains silicon which has been eluted bythe etching process, and the used phosphoric acid aqueous solution issent to a recycling unit and the silicon contained in the phosphoricacid aqueous solution is removed. In this manner, the used phosphoricacid aqueous solution is recycled by removing the silicon in therecycling unit, and is returned to the processing bath again to be usedagain.

However, the used phosphoric acid aqueous solution has conventionallybeen sent to the recycling unit, regardless of the siliconconcentration.

When a phosphoric acid aqueous solution from which silicon cannot beremoved, or a phosphoric acid aqueous solution from which it takes timeto remove silicon is sent to the recycling unit, crystals are generatedwithin the recycling unit or a pipe line, or a trouble occurs in aninternal structure of the recycling unit.

SUMMARY

One aspect of the present disclosure provides a substrate liquidprocessing apparatus comprising: a liquid processing unit configured tostore a processing liquid and a substrate and process the substrateusing the processing liquid, the processing liquid including aphosphoric acid aqueous solution; a phosphoric acid aqueous solutionsupply unit configured to supply the phosphoric acid aqueous solution tothe liquid processing unit; a discharge line connected to the liquidprocessing unit, and configured to discharge the processing liquid; areturn line switchably connected to the discharge line, and configuredto return the processing liquid to the liquid processing unit; arecycling line switchably connected to the discharge line, and includinga recycling unit configured to recycle the processing liquid; and awaste line switchably connected to the discharge line, and configured todiscard the processing liquid to the outside.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating an entire substrate liquid processingsystem.

FIG. 2 is a side view illustrating a substrate liquid processingapparatus.

FIG. 3 is a plan view illustrating the substrate liquid processingapparatus.

FIG. 4 is an operation diagram illustrating a substrate liquidprocessing method.

FIG. 5 is an operation diagram illustrating the substrate liquidprocessing method.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawing, which form a part hereof. The illustrativeembodiments described in the detailed description, drawing, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

The present disclosure has been made in view of these problems, and anobject thereof is to provide a substrate liquid processing apparatusthat uses a recycling unit according to a silicon concentration in aused phosphoric acid aqueous solution so as to efficiently use therecycling unit, a substrate liquid processing method, and a storagemedium.

One aspect of the present disclosure provides a substrate liquidprocessing apparatus comprising: a liquid processing unit configured tostore a processing liquid and a substrate and process the substrateusing the processing liquid, the processing liquid including aphosphoric acid aqueous solution; a phosphoric acid aqueous solutionsupply unit configured to supply the phosphoric acid aqueous solution tothe liquid processing unit; a discharge line connected to the liquidprocessing unit, and configured to discharge the processing liquid; areturn line switchably connected to the discharge line, and configuredto return the processing liquid to the liquid processing unit; arecycling line switchably connected to the discharge line, and includinga recycling unit configured to recycle the processing liquid; and acontroller. The controller processes the substrate in the liquidprocessing unit, and switches the processing liquid discharged from thedischarge line, from the recycling line, to a waste line in which theprocessing liquid is discarded through the discharge line to theoutside, according to a concentration of an elution component elutedfrom the substrate.

In the above-described substrate liquid processing apparatus, thecontroller switches the processing liquid discharged from the dischargeline, to the return line without sending the processing liquid to therecycling line according to the concentration of the elution componenteluted from the substrate.

In the above-described substrate liquid processing apparatus, thecontroller processes the substrate in the liquid processing unit, andswitches the processing liquid discharged from the discharge line, tothe recycling line when the concentration of the elution componenteluted from the substrate reaches a predetermined recyclingconcentration, switches the processing liquid discharged from thedischarge line, to the waste line in which the processing liquid isdiscarded from the discharge line to the outside when the concentrationof the elution component eluted from the substrate reaches apredetermined waste concentration, and switches the processing liquiddischarged from the discharge line, to the return line, without sendingthe processing liquid to the recycling line when the concentration ofthe elution component eluted from the substrate does not reach thepredetermined recycling concentration.

In the above-described substrate liquid processing apparatus, aphosphoric acid concentration measuring unit configured to measure aphosphoric acid concentration of the processing liquid is provided, aheating tank configured to heat the processing liquid is provided nearthe liquid processing unit in the return line, and a water supply unitis connected to the liquid processing unit, and the controller, based ona signal from the phosphoric acid concentration measuring unit, heatsthe processing liquid by the heating tank when the phosphoric acidconcentration is lower than a predetermined phosphoric acidconcentration, and supplies water from the water supply unit to theliquid processing unit when the phosphoric acid concentration is higherthan the predetermined phosphoric acid concentration.

In the above-described substrate liquid processing apparatus, theconcentration of the elution component eluted from the substrate isobtained by an elution component concentration measuring unit providedin the discharge line.

In the above-described substrate liquid processing apparatus, as theconcentration of the elution component eluted from the substrate, theconcentration of the elution component in the processing liquid isobtained after elapse of a predetermined time obtained by a previouslyconducted experiment.

Another aspect of the present disclosure provides a method of performinga liquid processing on a substrate, the method comprising: processingthe substrate using a processing liquid in a liquid processing unit, theprocessing liquid including a phosphoric acid aqueous solution;supplying the phosphoric acid aqueous solution to the liquid processingunit from a phosphoric acid aqueous solution supply unit; dischargingthe processing liquid within the liquid processing unit from a dischargeline; returning the processing liquid to the liquid processing unit by areturn line switchably connected to the discharge line; and recyclingthe processing liquid by a recycling line switchably connected to thedischarge line, and including a recycling unit configured to recycle theprocessing liquid. The controller processes the substrate in the liquidprocessing unit, and switches the processing liquid discharged from thedischarge line, from the recycling line, to a waste line in which theprocessing liquid is discarded through the discharge line to theoutside, according to a concentration of an elution component elutedfrom the substrate.

In the above-described method, the controller switches the processingliquid discharged from the discharge line, to the return line withoutsending the processing liquid to the recycling line according to theconcentration of the elution component eluted from the substrate.

In the above-described method, the controller processes the substrate inthe liquid processing unit, and switches the processing liquiddischarged from the discharge line, to the recycling line when theconcentration of the elution component eluted from the substrate reachesa predetermined recycling concentration, switches the processing liquiddischarged from the discharge line, to the waste line in which theprocessing liquid is discarded from the discharge line to the outsidewhen the concentration of the elution component eluted from thesubstrate reaches a predetermined waste concentration, and switches theprocessing liquid discharged from the discharge line, to the returnline, without sending the processing liquid to the recycling line whenthe concentration of the elution component eluted from the substratedoes not reach the predetermined recycling concentration.

In the above-described method, a phosphoric acid concentration measuringunit configured to measure a phosphoric acid concentration of theprocessing liquid is provided, a heating tank configured to heat theprocessing liquid is provided near the liquid processing unit in thereturn line, and a water supply unit is connected to the liquidprocessing unit, and the controller, based on a signal from thephosphoric acid concentration measuring unit, heats the processingliquid by the heating tank when the phosphoric acid concentration islower than a predetermined phosphoric acid concentration, and supplieswater from the water supply unit to the liquid processing unit when thephosphoric acid concentration is higher than the predeterminedphosphoric acid concentration.

In the above-described method, the concentration of the elutioncomponent eluted from the substrate is obtained by an elution componentconcentration measuring unit provided in the discharge line.

In the above-described method, as the concentration of the elutioncomponent eluted from the substrate, the concentration of the elutioncomponent in the processing liquid is obtained after elapse of apredetermined time obtained by a previously conducted experiment.

Yet another aspect of the present disclosure provides a storage mediumcausing a computer to execute a method of performing a liquid processingon a substrate, the method comprising: processing the substrate using aprocessing liquid in a liquid processing unit, the processing liquidincluding a phosphoric acid aqueous solution; supplying the phosphoricacid aqueous solution to the liquid processing unit from a phosphoricacid aqueous solution supply unit; discharging the processing liquidwithin the liquid processing unit from a discharge line; returning theprocessing liquid to the liquid processing unit by a return lineswitchably connected to the discharge line; and recycling the processingliquid by a recycling line switchably connected to the discharge line,and including a recycling unit configured to recycle the processingliquid. The controller processes the substrate in the liquid processingunit, and switches the processing liquid discharged from the dischargeline, from the recycling line, to a waste line in which the processingliquid is discarded through the discharge line to the outside, accordingto a concentration of an elution component eluted from the substrate.

According to the present disclosure, the recycling unit may be usedaccording to the silicon concentration in the used phosphoric acidaqueous solution so that the recycling unit may be efficiently used.

<Exemplary Embodiment of Present Disclosure>

Hereinafter, an exemplary embodiment of the present disclosure will bedescribed with reference to FIGS. 1 to 4. First, an entire substrateliquid processing system 1A in which a substrate liquid processingapparatus 1 according to the present disclosure is incorporated will bedescribed.

As illustrated in FIG. 1, the substrate liquid processing system 1Aincludes a carrier carry-in/out section 2, a lot forming section 3, alot placing section 4, a lot conveyance section 5, a lot processingsection 6, and a controller 7.

Among these, the carrier carry-in/out section 2 performs carry-in/out ofcarriers 9 in each of which a plurality of substrates (silicon wafers) 8(e.g., 25 sheets) in a horizontal posture are accommodated while alignedin a vertical direction.

The carrier carry-in/out section 2 is provided with a carrier stage 10on which the plurality of carriers 9 are placed, a carrier conveyancemechanism 11 configured to convey the carriers 9, carrier stocks 12 and13 that temporarily store the carriers 9, and a carrier placing table 14on which the carriers 9 are placed. Here, the carrier stock 12temporarily stores the substrates 8 to become products before thesubstrates 8 are processed in the lot processing section 6. The carrierstock 13 temporarily stores the substrates 8 to become products afterthe substrates 8 are processed in the lot processing section 6.

Then, the carrier carry-in/out section 2 conveys the carrier 9 carriedinto the carrier stage 10 from the outside, to the carrier stock 12 orthe carrier placing table 14 using the carrier conveyance mechanism 11.The carrier carry-in/out section 2 conveys the carrier 9 placed on thecarrier placing table 14 to the carrier stock 13 or the carrier stage 10using the carrier conveyance mechanism 11. The carrier 9 conveyed to thecarrier stage 10 is carried to the outside.

The lot forming section 3 forms a lot including a plurality ofsubstrates 8 (e.g., 50 sheets) to be simultaneously processed bycombining the substrates 8 accommodated in one or more carriers 9.Meanwhile, when the lot is formed, pattern-formed surfaces of thesubstrates 8 may face each other, or all pattern-formed surfaces of thesubstrates 8 may be directed toward one side.

The lot forming section 3 is provided with a substrate conveyancemechanism 15 configured to convey the plurality of substrates 8.Meanwhile, the substrate conveyance mechanism 15 may change the postureof the substrates 8 from a horizontal posture to a vertical posture, andfrom a vertical posture to a horizontal posture during the conveyance ofthe substrates 8.

Then, the lot forming section 3 conveys the substrates 8 from thecarrier 9 placed on the carrier placing table 14 to the lot placingsection 4 using the substrate conveyance mechanism 15, and places thesubstrates 8 forming the lot in the lot placing section 4. Further, thelot forming section 3 conveys the lot placed in the lot placing section4 to the carrier 9 placed on the carrier placing table 14 by thesubstrate conveyance mechanism 15. Meanwhile, the substrate conveyancemechanism 15 includes, as a substrate support configured to support theplurality of substrates 8, two types of substrate supports, that is, anunprocessed substrate support that supports unprocessed substrates 8(before the substrates 8 are conveyed by the lot conveyance section 5),and a processed substrate support that supports processed substrates 8(after the substrates 8 are conveyed by the lot conveyance section 5).Accordingly, for example, particles adhering to, for example, theunprocessed substrates 8 may be suppressed from sticking to, forexample, the processed substrates 8.

In the lot placing section 4, the lots conveyed between the lot formingsection 3 and the lot processing section 6 by the lot conveyance section5 are temporarily placed (on standby) on a lot placing table 16.

The lot placing section 4 is provided with a carry-in side lot placingtable 17 on which an unprocessed lot is placed (before the lot isconveyed by the lot conveyance section 5), and a carry-out side lotplacing table 18 on which a processed lot is placed (after the lot isconveyed by the lot conveyance section 5). In each of the carry-in sidelot placing table 17 and the carry-out side lot placing table 18, theplurality of substrates 8 for one lot are placed in a vertical postureto be aligned in the front-rear direction.

In the lot placing section 4, the lot formed by the lot forming section3 is placed on the carry-in side lot placing table 17, and is carriedinto the lot processing section 6 through the lot conveyance section 5.In the lot placing section 4, the lot carried out of the lot processingsection 6 through the lot conveyance section 5 is placed on thecarry-out side lot placing table 18, and is conveyed to the lot formingsection 3.

The lot conveyance section 5 conveys lots between the lot placingsection 4 and the lot processing section 6 or within the lot processingsection 6.

The lot conveyance section 5 is provided with a lot conveyance mechanism19 configured to convey lots. The lot conveyance mechanism 19 isconstituted by a rail 20 arranged along the lot placing section 4 andthe lot processing section 6, and a moving body 21 which holds theplurality of substrates 8 and moves along the rail 20. A substrateholder 22 configured to hold the plurality of substrates 8 aligned in avertical posture in a front-rear direction is provided in the movingbody 21 so as to freely advance and retreat.

The lot conveyance section 5 receives the lot placed on the carry-inside lot placing table 17 by the substrate holder 22 of the lotconveyance mechanism 19, and delivers the received lot to the lotprocessing section 6. The lot conveyance section 5 receives the lotprocessed in the lot processing section 6 by the substrate holder 22 ofthe lot conveyance mechanism 19, and delivers the lot to the carry-outside lot placing table 18. The lot conveyance section 5 conveys the lotwithin the lot processing section 6 using the lot conveyance mechanism19.

The lot processing section 6 performs processings such as, for example,etching, cleaning, or drying, on one lot constituted by the plurality ofsubstrates 8 aligned in the vertical posture in the front-reardirection.

In the lot processing section 6, a drying device 23 configured to drythe substrates 8, a substrate holder cleaning device 24 configured toclean the substrate holder 22, a cleaning device 25 configured to cleanthe substrates 8, and two etching devices (substrate liquid processingapparatuses) 1 according to the present disclosure, which are configuredto etch the substrates 8, are provided to be aligned.

The drying device 23 includes a processing bath 27, and a substrate liftmechanism 28 provided in the processing bath 27 so as to be able to moveup and down. A drying processing gas (e.g., isopropyl alcohol (IPA)) issupplied to the processing bath 27. In the substrate lift mechanism 28,the plurality of substrates 8 for one lot are held to be aligned in thevertical posture in the front-rear direction. The drying device 23receives the lot from the substrate holder 22 of the lot conveyancemechanism 19 by the substrate lift mechanism 28, and raises and lowersthe lot by the substrate lift mechanism 28 so that the substrates 8 aredried by the drying processing gas supplied to the processing bath 27.The drying device 23 delivers the lot from the substrate lift mechanism28 to the substrate holder 22 of the lot conveyance mechanism 19.

The substrate holder cleaning device 24 includes a processing bath 29,and is configured to supply a cleaning processing liquid and a dryinggas to the processing bath 29. The substrate holder cleaning device 24supplies the cleaning processing liquid to the substrate holder 22 ofthe lot conveyance mechanism 19, and supplies the drying gas to thesubstrate holder 22 so as to clean the substrate holder 22.

The cleaning device 25 includes a cleaning processing bath 30 and arinse processing bath 31, and substrate lift mechanisms 32 and 33 areprovided in the processing baths 30 and 31, respectively, so as to beable to move up and down. A cleaning processing liquid (e.g., SC-1) isstored in the cleaning processing bath 30. A rinse processing liquid(e.g., pure water) is stored in the rinse processing bath 31.

The etching device 1 includes a processing bath 34 for etching and aprocessing bath 35 for rinsing, and substrate lift mechanisms 36 and 37are provided in the processing baths 34 and 35, respectively, so as tobe able to move up and down. An etching processing liquid (a phosphoricacid aqueous solution) is stored in the processing bath 34 for etching.A rinse processing liquid (e.g., pure water) is stored in the processingbath 35 for rinsing. As described above, the etching device 1constitutes the substrate liquid processing apparatus according to thepresent disclosure.

The cleaning device 25 and the etching device 1 have the sameconfiguration. Hereinafter, the etching device (the substrate liquidprocessing apparatus) I will be described. In the substrate liftmechanism 36, the plurality of substrates 8 for one lot are held to bealigned in the vertical posture in the front-rear direction. In theetching device 1, the lot is received from the substrate holder 22 ofthe lot conveyance: mechanism 19 by the substrate lift mechanism 36, andis raised and lowered by the substrate lift mechanism 36 while beingimmersed in the etching processing liquid of the processing bath 34 sothat the substrates 8 are etched. Then, the etching device 1 deliversthe lot from the substrate lift mechanism 36 to the substrate holder 22of the lot conveyance mechanism 19. The lot is received by the substratelift mechanism 37 from the substrate holder 22 of the lot conveyancemechanism 19, and is raised and lowered by the substrate lift mechanism37 while being immersed in the rinse processing liquid of the processingbath 35 so that the substrates 8 are rinsed. Thereafter, the lot isdelivered to the substrate holder 22 of the lot conveyance mechanism 19from the substrate lift mechanism 37.

The controller 7 controls operations of respective units of thesubstrate liquid processing system 1A (the carrier carry-in/out section2, the lot forming section 3, the lot placing section 4, the lotconveyance section 5, the lot processing section 6, and the etchingdevice 1).

The controller 7 is constituted by, for example, a computer, andincludes a computer readable storage medium 38. A program that controlsvarious processings to be executed in the substrate liquid processingapparatus 1 is stored in the storage medium 38. The controller 7 readsand executes the program stored in the storage medium 38 to control theoperation of the substrate liquid processing apparatus 1. Meanwhile, theprogram has been recorded in the computer readable storage medium 38,and may be installed from another storage medium to the storage medium38 of the controller 7. As the computer readable storage medium 38, forexample, a hard disk (HD), a flexible disk (FD), a compact disk (CD), amagneto optical disk (MO), and a memory card may be exemplified.

As described above, in the processing bath 34 of the etching device 1,an aqueous solution of a chemical agent (phosphoric acid) (i.e., aphosphoric acid aqueous solution) at a predetermined concentration isused as a processing liquid (an etching liquid) to perform a liquidprocessing (an etching processing) on the substrates 8.

The etching device (the substrate liquid processing apparatus) 1, asillustrated in FIGS. 2 and 3, includes: a liquid processing unit 39configured to store a processing liquid containing a phosphoric acidaqueous solution at a predetermined concentration and process thesubstrates 8; a phosphoric acid aqueous solution supply unit 40configured to supply the phosphoric acid aqueous solution to the liquidprocessing unit 39; a pure water supply unit 41 configured to supplypure water with which the phosphoric acid aqueous solution is diluted; aprocessing liquid circulating line 42 configured to circulate theprocessing liquid stored in the liquid processing unit 39; and aprocessing liquid discharge unit 43 configured to discharge theprocessing liquid from the liquid processing unit 39.

The liquid processing unit 39 includes the processing bath 34 foretching, whose top side is opened, and an outer bath 44 provided aroundthe upper portion of the processing bath 34 and having a top opening.The processing liquid is stored in the processing bath 34 and the outerbath 44. The processing bath 34 stores the processing liquid in whichthe substrates 8 are immersed by the substrate lift mechanism 36 andsubjected to a liquid processing. The outer bath 44 stores theprocessing liquid overflowing from the processing bath 34, and suppliesthe processing liquid to the processing bath 34 by the processing liquidcirculating line 42. Meanwhile, in the substrate lift mechanism 36, theplurality of substrates 8 are held while being aligned at intervals in avertically erected posture in a horizontal direction.

The phosphoric acid aqueous solution supply unit 40 supplies an aqueoussolution of a chemical agent (phosphoric acid) (a phosphoric acidaqueous solution) having a concentration lower than the processingliquid, to the liquid processing unit 39. The phosphoric acid aqueoussolution supply unit 40 includes an aqueous solution supply source 45that supplies a phosphoric acid aqueous solution at a predeterminedconcentration and a predetermined temperature. The aqueous solutionsupply source 45 is connected to the outer bath 44 of the liquidprocessing unit 39 via a phosphoric acid aqueous solution supply line45A having switching valves 62 and 64. The switching valves 62 and 64are connected to the controller 7, and controlled to be opened andclosed by the controller 7.

The pure water supply unit 41 supplies pure water in order to replenishmoisture evaporated by heating (boiling) the processing liquid. The purewater supply unit 41 includes a pure water supply source 47 thatsupplies pure water at a predetermined temperature. The pure watersupply source 47 is connected to the outer bath 44 of the liquidprocessing unit 39 via a flow rate regulator 48. The flow rate regulator48 is connected to the controller 7, and the opening/closing and theflow rate of the flow rate regulator 48 are controlled by the controller7.

The processing liquid circulating line 42 includes a processing liquidsupply nozzle 49 disposed below the substrates 8 held by the substratelift mechanism 36 within the processing bath 34, and a circulation flowpath 50 formed between the bottom portion of the outer bath 44 of theliquid processing unit 39 and the processing liquid supply nozzle 49. Inthe circulation flow path 50, a supply pump 51, a healer 52, a filter53, and a densitometer (a concentration measuring unit) 55 aresequentially provided. The supply pump 51 and the heater 52 areconnected to the controller 7, and controlled to be driven by thecontroller 7. The processing liquid circulating line 42 circulates theprocessing liquid from the outer bath 44 to the processing bath 34 bydriving the supply pump 51. Here, the processing liquid is heated to apredetermined temperature by the heater 52. Meanwhile, the processingliquid circulating line 42 including the supply pump 51, the heater 52,and the filter 53 serves as a processing liquid supply unit thatsupplies the processing liquid to the liquid processing unit 39. Thedensitometer 55 serves as a phosphoric acid concentration measuring unitthat measures the concentration of phosphoric acid in the processingliquid, and also serves as an elution component concentration measuringunit that measures the concentration of silicon (an elution componentconcentration) eluted from the substrates 8 in the processing liquid.The results measured by the densitometer 55 are sent to the controller7.

As illustrated in FIG. 3, the processing liquid supply nozzle 49 has atubular shape extending in the arrangement direction of the plurality ofsubstrates 8. Then, the processing liquid is ejected toward thesubstrates 8 held by the substrate lift mechanism 36 from a plurality ofejecting holes 49 a perforated in the peripheral surface of theprocessing liquid supply nozzle 49.

The processing liquid discharge unit 43 includes a discharge line 82connected to the bottom portion of the processing bath 34 of the liquidprocessing unit 39, and a densitometer 43A and a switching valve 66 areprovided in the discharge line 82. Among these, the switching valve 66is connected to the controller 7, and controlled to be opened/closed bythe controller 7. A cooling tank 85 is connected to the discharge line82 in which the switching valve 66 is provided.

The densitometer 43A provided in the discharge line 82 serves as aphosphoric acid concentration measuring unit that measures theconcentration of phosphoric acid in the processing liquid, and alsoserves as an elution component concentration measuring unit thatmeasures the concentration of silicon (an elution componentconcentration) eluted from the substrates 8 in the processing liquid. Abypass line 83 (a discharge line) that bypasses the cooling tank 85 isconnected to the discharge line 82, is provided with a switching valve68, and is connected to the discharge line 82 to be described below.

A waste line 87 is connected to the discharge line 82 at the downstreamside of a switching valve 67 so as to discard the processing liquid tothe outside through a switching valve 69. A recycling line 90 isconnected to the discharge line 82 at the downstream side of theswitching valve 67 through a switching valve 70. The recycling line 90includes a recycling unit 91 that recycles the processing liquid byremoving silicon in the processing liquid.

Among these, the recycling unit 91 includes a recycler 91A that removessilicon in the processing liquid, and a storage 91B that stores theprocessing liquid from which silicon is removed.

A switching valve 71 is provided in the discharge line 82 at thedownstream side of the switching valve 67. The outlet side of therecycling unit 91 joins a return line 80 provided with the switchingvalve 71 through a switching valve 72 at a junction 80 a. A switchingvalve 73 is provided in the return line 80 at the downstream side of thejunction 80 a, and the return line 80 extends to the phosphoric acidaqueous solution supply unit 40 side. The return line 80 joins thephosphoric acid aqueous solution supply line 45A of the phosphoric acidaqueous solution supply unit 40 through a switching valve 61 at ajunction 80 b. Meanwhile, the outlet side of the recycling unit 91 maynot join the return line 80 provided with the switching valve 71 throughthe switching, valve 72 at the junction 80 a. A return line (notillustrated) different from the return line 80) may extend to thephosphoric acid aqueous solution supply unit 40 side through theswitching valve 72, and then, join the phosphoric acid aqueous solutionsupply line 45A of the phosphoric acid aqueous solution supply unit 40through the switching valve 61 at the junction 80 b.

A switching valve 64 is provided at the downstream side of the junction80 b of the phosphoric acid aqueous solution supply line 45A. A branchline 45B having a switching valve 63 is formed at the downstream side ofthe junction 80 b of the phosphoric acid aqueous solution supply line45A, and a heating tank 60 is connected to the branch line 45B.

An introduction line 60A having a switching valve 65 is connected to thebottom portion of the heating tank 60, and joins the phosphoric acidaqueous solution supply line 45A at the downstream of the switchingvalve 64 to extend to the outer bath 44 of the liquid processing unit39.

Meanwhile, among the above components, the heating tank 60, the coolingtank 85, the recycling unit 91, and the switching valves 61 to 73 arecontrolled to be driven by the controller 7.

The substrate liquid processing apparatus 1 is configured as describedabove, and processes the substrates 8 when the controller 7 controlsoperations of the respective units (the carrier carry-in/out section 2,the lot forming section 3, the lot placing section 4, the lot conveyancesection 5, the lot processing section 6, and the etching device 1)according to, for example, a substrate liquid processing program storedin the storage medium 38.

Hereinafter, the operation of the present exemplary embodimentconfigured as described above, that is, the substrate liquid processingmethod will be described. First, the phosphoric acid aqueous solution(the processing liquid) at a predetermined phosphoric acid concentrationand a predetermined temperature is supplied to the outer bath 44 of theliquid processing unit 39 by the phosphoric acid aqueous solution supplyunit 40 of the etching device 1. Next, the processing liquid from theouter bath 44 is heated by the heater 52 of the processing liquidcirculating line 42 to a predetermined phosphoric acid concentration(e.g., 87.4 wt %) and a predetermined temperature (e.g., 160° C.), andis stored in the processing bath 34 of the liquid processing unit 39.Here, the moisture is evaporated by the heating of the heater 52 tobecome air bubbles and the air bubbles rise in the processing liquidwhile the processing liquid is placed in a boiling state. In this case,since the concentration of the processing liquid is increased, purewater in an amount corresponding to the amount of moisture evaporated bythe heating is supplied to the outer bath 44 of the liquid processingunit 39 by the pure water supply unit 41 so that the processing liquidis diluted with the pure water. Then, the substrates 8 are immersed bythe substrate lift mechanism 36 in the processing bath 34 that storesthe processing liquid at a predetermined concentration and apredetermined temperature so that the substrates 8 are subjected to anetching processing (liquid processing) by the processing liquid. Here,the air bubbles generated by evaporation of the moisture rise in theprocessing liquid, and the processing liquid is circulated by the risingair bubbles, thereby promoting the etching processing by the processingliquid.

During the liquid processing, the phosphoric acid aqueous solutionsupply unit 40, the pure water supply unit 41, and the supply pump 51and the heater 52 of the processing liquid circulating line 42 arecontrolled by the controller 7 to maintain the processing liquid at apredetermined concentration and a predetermined temperature.

In this case, the controller 7 drives the supply pump 51 to circulatethe processing liquid through the circulation flow path 50, and drivesthe heater 52 to maintain the temperature of the processing liquid at apredetermined temperature so that the liquid processing of thesubstrates 8 is initiated.

At a predetermined timing after the liquid processing initiation, thecontroller 7 measures the phosphoric acid concentration of theprocessing liquid by the densitometer 55. As in the liquid processinginitiation, the controller 7 drives the supply pump 51 to circulate theprocessing liquid through the circulation flow path 50, and drives theheater 52 to maintain the temperature of the processing liquid at apredetermined temperature.

Meanwhile, at predetermined time intervals during the liquid processing,a new processing liquid (a phosphoric acid aqueous solution) is suppliedto the outer bath 44 of the liquid processing unit 39 by the phosphoricacid aqueous solution supply unit 40. At the same time, the processingliquid is discharged from the processing bath 34 of the liquidprocessing unit 39 through the discharge line 82, and the processingliquid discharged from the processing bath 34 to the discharge line 82is guided to the cooling tank 85.

In this manner, a new processing liquid in a certain amount may besupplied to the outer bath 44 of the liquid processing unit 39, and theprocessing liquid in substantially the same amount as the amount of thesupplied new processing liquid may be discharged from the processingbath 34 of the liquid processing unit 39 through the discharge line 82,so as to keep the phosphoric acid concentration within the processingbath 34 of the liquid processing unit 39 constant.

Meanwhile, in the processing bath 34 of the liquid processing unit 39, aliquid processing is performed on the substrates 8 composed of siliconwafers, and thus, silicon is eluted from the substrates 8 to theprocessing liquid.

The phosphoric acid concentration and the silicon concentration in theprocessing liquid discharged to the discharge line 82 from theprocessing bath 34 are measured by the densitometer 43A of the dischargeline 82.

Subsequently, the measurement signals from the densitometer 43A are sentto the controller 7.

As illustrated in FIG. 4, the controller 7 sends the processing liquidin the cooling tank 85 to the recycling unit 91 via the switching valves67 and 70 based on the measurement signals from the densitometer 43A sothat the silicon concentration in the processing liquid becomesconstant. In the recycler 91A of the recycling unit 91, silicon in theprocessing liquid is removed. The processing liquid from which thesilicon is removed is stored in the storage 91B, passes through thereturn line 80 via the switching valves 72 and 73, is sent to thephosphoric acid aqueous solution supply line 45A of the phosphoric acidaqueous solution supply unit 40 through the switching valve 61, and isreturned to the outer bath 44 of the liquid processing unit 39.

In this manner, the processing liquid within the processing bath 34 ofthe liquid processing unit 39 is guided to the recycling unit 91 throughthe cooling tank 85, and silicon is removed in the recycling unit 91.Then, the processing liquid from which the silicon is removed isreturned into the processing bath 34 of the liquid processing unit 39 sothat the silicon concentration in the processing liquid may be keptsubstantially constant near the liquid processing and recyclingconcentration (see FIG. 4).

As such a liquid processing is continued, the silicon concentration inthe processing liquid may rapidly increase from the liquid processingand recycling concentration and reach a waste concentration.

After the silicon concentration has reached the waste concentration,when the processing liquid is sent to the recycling unit 91 and isrecycled by the recycling unit 91, the silicon concentration becomesexcessively high. Thus, crystals are generated within the recycling unit91 or a pipe line, and, a trouble occurs in the internal structure ofthe recycling unit 91.

According to the present exemplary embodiment, when the siliconconcentration in the processing liquid has reached the wasteconcentration, the controller 7 sends the processing liquid in thecooling tank 85 to the waste line 87 from the discharge line 82 throughthe switching valve 69, and discards the processing liquid from thewaste line 87 to the outside. Thus, the processing liquid at a highsilicon concentration may not be sent to the recycling unit 91 so thatthe internal structure of the recycling unit 91 is not damaged ordeteriorated. Further, the recycling unit 91 may be effectively utilizedover a long period of time.

Meanwhile, in the present exemplary embodiment, an example in which theprocessing liquid in the processing bath 34 of the liquid processingunit 39 is guided to the recycling unit 91 through the cooling tank 85has been described, but the present disclosure is not limited thereto.The processing liquid in the processing bath 34 of the liquid processingunit 39 may be guided to the recycling unit 91 side by bypassing thecooling tank 85 using the bypass line 83.

Meanwhile, based on the phosphoric acid concentration in the processingliquid discharged from the processing bath 34 to the discharge line 82,which has been measured by the densitometer 43A of the discharge line82, when the phosphoric acid concentration is lower than a predeterminedphosphoric acid concentration, the controller 7 sends the processingliquid returned to the phosphoric acid aqueous solution supply line 45Athrough the junction 80 b by the return line 80, to the heating tank 60.Then, the controller 7 increases the phosphoric acid concentration byheating the processing liquid by the heating tank 60, and returns theprocessing liquid to the outer bath 44 of the liquid processing unit 39through the introduction line 60A.

Meanwhile, when the phosphoric acid concentration is higher than apredetermined phosphoric acid concentration, the controller 7 suppliespure water to the outer bath 44 of the liquid processing unit 39 by thepure water supply unit 41, thereby decreasing the phosphoric acidconcentration of the processing liquid.

In this manner, the phosphoric acid concentration in the processingliquid within the processing bath 34 of the liquid processing unit 39may be kept substantially constant.

<Modification>

Hereinafter, a modification of the present disclosure will be describedwith reference to FIG. 5.

The configuration of the modification illustrated in FIG. 5 issubstantially the same as that of the exemplary embodiment illustratedin FIGS. 1 to 4, except for a control method by the controller 7.

In the modification illustrated in FIG. 5, the same parts as those inthe exemplary embodiment illustrated in FIGS. 1 to 4 will be denoted bythe same reference numerals as used in FIGS. 1 to 4, and detaileddescriptions thereof will be omitted.

At predetermined time intervals during the liquid processing, a newprocessing liquid (a phosphoric acid aqueous solution) is supplied tothe outer bath 44 of the liquid processing unit 39 by the phosphoricacid aqueous solution supply unit 40. At the same time, the processingliquid is discharged from the processing bath 34 of the liquidprocessing unit 39 through the discharge line 82, and the processingliquid discharged from the processing bath 34 to the discharge line 82is guided to the cooling tank 85.

In this manner, a new processing liquid in a certain amount may besupplied to the outer bath 44 of the liquid processing unit 39, and theprocessing liquid in substantially the same amount as the amount of thesupplied new processing liquid may be discharged from the processingbath 34 of the liquid processing unit 39 through the discharge line 82,so as to keep the phosphoric acid concentration within the processingbath 34 of the liquid processing unit 39 constant.

Meanwhile, in the processing bath 34 of the liquid processing unit 39, aliquid processing is performed on the substrates 8 composed of siliconwafers and thus silicon is eluted from the substrates 8 to theprocessing liquid.

The phosphoric acid concentration and the silicon concentration in theprocessing liquid discharged to the discharge line 82 from theprocessing bath 34 are measured by the densitometer 43A of the dischargeline 82.

Subsequently, the measurement signals from the densitometer 43A are sentto the controller 7.

As illustrated in FIG. 5, the controller 7 determines that immediatelyafter the liquid processing initiation, the silicon concentration in theprocessing liquid does not largely increase. Here, the controller 7sends the processing liquid in the cooling tank 85 from the switchingvalve 67 of the discharge line 82 to the switching valve 71.Subsequently, the controller 7 sends the processing liquid to thephosphoric acid aqueous solution supply line 45A of the phosphoric acidaqueous solution supply unit 40 through the return line 80 via theswitching valve 61 without using the recycling unit 91, and then,returns the processing liquid into the outer bath 44 of the liquidprocessing unit 39.

Meanwhile, since the processing liquid does not pass through therecycling unit 91, the silicon concentration in the processing liquidwithin the processing bath 34 gradually increases (the solid line inFIG. 5).

Next, the controller 7 determines that after the elapse of apredetermined time (t1) obtained by a previously conducted experiment,the silicon concentration in the processing liquid has reached arecycling concentration, and sends the processing liquid within thecooling tank 85 to the recycling unit 91, so that silicon in theprocessing liquid is removed in the recycling unit 91. Meanwhile, thecontroller 7 may confirm that the silicon concentration has reached therecycling concentration based on measurement signals from thedensitometer 43A without determining that after the elapse of apredetermined time (t1), the silicon concentration in the processingliquid has reached a recycling concentration.

Specifically, as illustrated in FIG. 5, based on the measurement signalsfrom the densitometer 43A, the controller 7 sends the processing liquidwithin the cooling tank 85 to the recycling unit 91 via the switchingvalves 67 and 70 so that the silicon concentration in the processingliquid drops from the solid line state to the broken line state. Then,silicon in the processing liquid is removed in the recycler 91A of therecycling unit 91. The processing liquid from which the silicon isremoved is stored in the storage 91B, passes through the return line 80via the switching valves 72 and 73, is sent to the phosphoric acidaqueous solution supply line 45A of the phosphoric acid aqueous solutionsupply unit 40 through the switching valve 61, and is returned to theouter bath 44 of the liquid processing unit 39.

In this manner, the processing liquid within the processing bath 34 ofthe liquid processing unit 39 is guided to the recycling unit 91 throughthe cooling tank 85, and silicon is removed in the recycling unit 91.Then, the processing liquid from which the silicon is removed isreturned into the processing bath 34 of the liquid processing unit 39 sothat the silicon concentration in the processing liquid may drop fromthe solid line state to the broken line state (see FIG. 5).

As such a liquid processing is continued, the silicon concentration inthe processing liquid gradually increases from the recyclingconcentration, and then, reaches a waste concentration after the elapseof a predetermined time (t2) obtained by a previously conductedexperiment.

After the silicon concentration has reached the waste concentration,when the processing liquid is sent to the recycling unit 91 and isrecycled by the recycling unit 91, the silicon concentration becomesexcessively high. Thus, crystals are generated within the recycling unit91 or a pipe line, and, a trouble occurs in an internal structure of therecycling unit 91.

According to the present exemplary embodiment, when the siliconconcentration in the processing liquid has reached the wasteconcentration, the controller 7 sends the processing liquid within thecooling tank 85 to the waste line 87 from the discharge line 82 throughthe switching valve 69 during a predetermined time (t3) obtained by apreviously conducted experiment, and discards the processing liquid fromthe waste line 87 to the outside. Thus, the processing liquid at a highsilicon concentration may not be sent to the recycling unit 91 so thatthe internal structure of the recycling unit 91 is not damaged ordeteriorated. Also, the recycling unit 91 may be effectively utilizedover a long period of time.

Meanwhile, after the liquid processing initiation, when the siliconconcentration in the processing liquid is lower than the recyclingconcentration, the processing liquid is returned to the liquidprocessing unit 39 side without being sent to the recycling unit 91.Thus, the recycling unit 91 is not unnecessarily operated. Therefore,the recycling efficiency of the recycling unit 91 may be maintained.

Meanwhile, in the present exemplary embodiment, an example in which theprocessing liquid in the processing bath 34 of the liquid processingunit 39 is guided to the recycling unit 91 through the cooling tank 85has been described, but the present disclosure is not limited thereto.The processing liquid in the processing bath 34 of the liquid processingunit 39 may be caused to bypass the cooling tank 85 using the bypassline 83.

Based on the phosphoric acid concentration in the processing liquiddischarged from the processing bath 34 to the discharge line 82, whichhas been measured by the densitometer 43A of the discharge line 82, whenthe phosphoric acid concentration is lower than a predeterminedphosphoric acid concentration, the controller 7 sends the processingliquid returned to the phosphoric acid aqueous solution supply line 45Athrough the junction 80 b by the return line 80, to the heating tank 60.Then, the controller 7 increases the phosphoric acid concentration byhealing the processing liquid by the heating tank 60, and returns theprocessing liquid to the outer bath 44 of the liquid processing unit 39through the introduction line 60A.

Meanwhile, when the phosphoric acid concentration is higher than apredetermined phosphoric acid concentration, the controller 7 suppliespure water to the outer bath 44 of the liquid processing unit 39 by thepure water supply unit 41, thereby decreasing the phosphoric acidconcentration of the processing liquid.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A substrate liquid processing apparatuscomprising: a liquid processing unit configured to store a processingliquid and a substrate and process the substrate using the processingliquid, the processing liquid including a phosphoric acid aqueoussolution; a phosphoric acid aqueous solution supply unit configured tosupply the phosphoric acid aqueous solution to the liquid processingunit; a discharge line connected to the liquid processing unit, andconfigured to discharge the processing liquid; a return line switchablyconnected to the discharge line, and configured to return the processingliquid to the liquid processing unit; a recycling line switchablyconnected to the discharge line, and including a recycling unitconfigured to recycle the processing liquid; and a waste line switchablyconnected to the discharge line, and configured to discard theprocessing liquid to the outside.
 2. The substrate liquid processingapparatus of claim 1, wherein the recycling line joins the return linethrough a switching valve.
 3. The substrate processing apparatus ofclaim 1, wherein the discharge line is connected to a cooling tank and abypass line that bypasses the cooling tank.
 4. The substrate liquidprocessing apparatus of claim 1, wherein the return line joins thephosphoric acid aqueous solution supply line of the phosphoric acidaqueous solution supply unit.
 5. The substrate liquid processingapparatus of claim 4, wherein the phosphoric acid aqueous solutionsupply line is provided with a branch line that is connected to aheating tank.